Phycotoxins ([phyco=seaweeds and algae] plus toxins) are a diverse group of substances produced by various aquatic plants in marine and fresh waters throughout the world. Not all aquatic plants produce toxins; and among those that do, not all, even from the same genera and species, produce toxins at all times and under all circumstances. Such toxins are associated with large fish kills and major kills of marine mammals. These toxins can also be found in shellfish.
Phycotoxins can also be produced by cyanobacteria. Five cyanobacteria are known to produce shellfish paralyzing phycotoxins, each of them having a characteristic composition with respect to the amount and type of phycotoxins produced (e.g., profile of phycotoxins):
(1) Cylindrospermopsis raciborskii, isolated from Brazil;
(2) Aphanizomenon flos-aquae, isolated from Portugal;
(3) Anabaena raciborskii , isolated from Australia;
(4) Lyngbya wollei, isolated from North America; and
(5) Aphanizomenon (Aph) gracile (Lemm) Lemm (Pereira P LMECYA40).
Neosaxitoxin and saxitoxin are two specific phycotoxins produced by dinoflagellate species of the genera Alexandrium sp., Piridinium sp. and Gimnodinium sp. and cyanobacteria.
Neosaxitoxin and saxitoxin acts as specific blockers of the voltage-dependent sodium channels present in excitable cells. Due to the inhibition of sodium channels, the transmission of a nervous impulse is blocked preventing the release of neurotransmitters at the neuromotor junction, which prevents muscular contraction. Due to these physiological effects, these compounds are potentially useful in pharmacology when used as muscular activity inhibitors in pathologies associated with muscular hyperactivity, such as muscular spasms and focal dystonias, when administered locally. These compounds can also inhibit sensory pathways and generate an anesthetic effect when administered locally.
However, these compounds are not available commercially in the quantities necessary to manufacture pharmaceutical compositions. Therefore, there exists a need for improved methods to produce phycotoxins having a definite compositional profile, particularly phycotoxin mixtures containing only neosaxitoxin and saxitoxin or GTX 2 and GTX 3.
Therefore, it is an object of the invention to provide improved methods for producing phycotoxins having a definite compositional profile, particularly phycotoxin mixtures containing only neosaxitoxin and saxitoxin or GTX 2 and GTX 3.
It is another object of the invention to provide a continuous method for culturing cyanobacteria for the production of phycotoxins having a definite compositional profile, particularly phycotoxin mixtures containing only neosaxitoxin and saxitoxin or GTX 2 and GTX 3.
It is another object of the invention to produce substantially pure phycotoxins using the methods described herein.